1. Field of the Invention
The present invention relates to monitoring storm conditions, especially for tropical storms, such as hurricanes.
2. Description of the Related Art
Tropical storms that develop into hurricanes are well-known to cause significant damage, injuries, and loss of life. Such tropical storms are also known as cyclones and typhoons. As used herein the terms “storm” and “tropical storm” each include any storm known as a tropical storm, hurricane, cyclone or typhoon.
Monetary costs can be large (on the order of hundreds of millions of dollars per year) and there can be major economic disruptions. Measuring oceanographic and meteorological conditions within and near these storms is important to determine their intensities, and enables more accurate predictions of strengths and locations at landfall where most damage occurs.
Present methods of data collection involve deploying meteorological sensors (e.g., dropsondes) from aircraft (e.g., hurricane hunters) and installing data collection buoys at fixed locations. Deployment of sensors from aircraft has been important but suffers from the deficiencies of: extensive personnel; multiple expensive missions; dangerous missions over long ranges; and discontinuous data collection. Measurement of oceanographic and meteorological data from fixed buoys, such as the buoys deployed by the National Data Buoy Center (NDBC), a component of the National Weather Service (NWS), National Oceanic and Atmospheric Administration (NOAA), have also been helpful. However fixed buoys also have deficiencies, including a major deficiency in that a storm may not pass near the fixed buoy. Other deficiencies are that fixed data collection buoys need to be large for mooring in deep water, and they are expensive.
There have been several efforts to develop autonomous buoys, or station-keeping buoys (e.g., for acoustic ocean surveillance for Department of Defense, DoD, applications). Several of these buoys use mechanical propulsion with power provided by batteries, solar cells, or engines. Some of these buoys use sails. These buoys have been designed for maintaining an approximate fixed geographical position.
Various free-drifting buoys have been developed. These buoys drift with prevailing currents and they are designed generally to minimize wind effects. For example, sub-surface drogues (i.e., drag devices) are used to increase drift with currents and decrease drift with winds.
Buoys have been deployed ahead of hurricanes. For example, NOAA and the Navy have deployed, by aircraft, an array of drifting buoys in the tropical Atlantic before hurricane seasons to help hurricane forecasting. These small buoys float partially submerged and have submerged drogues to further reduce effects of the wind in moving them.
To Applicant's knowledge, no buoys have been designed or deployed that attempt to position themselves along a target path relative to a center of the tropical storm as the storm propagates across the sea surface.